298 BULLETIN OF THE BUREAU OF FISHERIES. 
animal population of bottom, and other features which have direct application to the 
lakes as habitats for fish. ‘Therefore, one who wishes to investigate fresh-water fishes 
in their natural surroundings can do so at Madison and know more about environmental 
conditions than anywhere else in America. 
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Fic. 2.—Lake Mendota and Lake Wingra, the two lakes near Madison, Wis., in which the yellow perch was chiefly studied. 
{For dimensions see Table 1.} 
Two of the Madison lakes (fig. 2), differing as much as possibie, have been utilized 
for perch studies. Though both of these are of glacial origin, one is large and deep, 
with comparatively cool waters that become stratified thermally during the summer; the 
other is small, shallow, has wide seasonal variations in temperature, and shows no thermal 
stratification during the warmer months. The two lakes are compared in Table 1. 
